Electron discharge device



June; 2, 1936. J. w. MARDEN ELECTRON DI SCHARGE DEVI CE Filed April 5, 1950 n VIII INVENTOR I M MAI-EDEN.

Patented June 2, 1936 PATENT OFFICE ELECTRON DISCHARGE DEVICE John Wesley Marden, East Orange, N. J assignor to Westinghouse Lamp Company, a corporation of Pennsylvania Application April 5, 1930, Serial No. 441,997

3 Claims.

This invention relates to an electron discharge device and relates more particularly to devices of the above character employing a filament, grid and anode used in connection with radio receiving and transmitting apparatus.

It is an object of the present invention to provide a radio tube so constructed as to avoid the r effectively avoid back emission and at the same time operate to entrap electrons and avoid a hum.

The above is accomplished by providing plate having a plurality of tortuous passages so that the heat will find its way out by reflecting from the surfaces of the passages but the electrons when making contact with the surfaces of the passages will be absorbed by the plate and prevented from reaching the filament lead or any parts of the internal structure of the device.

It has been found that an anode having a double wall of mesh material gives satisfactory results since this construction provides a multiplicity of elongated or sinuous passages through which heat from the filament may travel and effectively entrap electrons which may attempt to escape and collect in other parts of the structure thus avoiding the detrimental A. C. hum.

Although a double wall of mesh may be used it has been found that What is termed a twill mesh also gives satisfactory results since this type of mesh is so fabricated that the apertures or passages therethrough are relatively long and prevent the escape of electrons.

Other types of plate material may be employed as for example a plate of sheet metal having apertures punched therein so as to throw a flange or burr around each aperture thus producing a plurality of relatively long passages, or a double wall of this type of perforated sheet metal may be employed with the apertures in the respective walls in staggered relation.

The invention will be more clearly understood from the following description together with the accompanying drawing in which,

Fig. 1 is a side elevational view of a radio tube having a plate constructed in accordance with the present invention.

Fig. 2 is an enlarged cross sectional view taken on lines IIII in Fig. 1.

Fig. 3 is an enlarged fragmentary view of a portion of a double wall anode shown in Fig. 2.

Fig. 4 is a fragmentary view of a fabric of twill mesh which may be used in place of the double wall shown in Fig. 2, and

Fig. 5 is a modified form of anode material having elongated apertures.

As illustrated the invention may be applied to a radio tube comprising a bulb l0 having a mount H sealed thereto at I2 in usual manner. A base l3 may be provided as is common in devices of this type. The mount may include a press M in which lead wires I5, l6, l1, l8, and I9 are embedded and connected to contact pins 2|, 22, 23,

24, and 25 extending from the base l3.

A bridge piece 26 of insulating material secured to the upper ends of support wires l5 and I9 serves to hold one end of a cathode assembly 21 as well as one end of a grid 28 in spaced relation. The lower ends of a filament 29 extending from the cathode assembly are secured to support Wires l6 and H and the grid is secured to support wire IS. The support wire l8 connects a sleeve 3! of the cathode assembly with one of the contact pins. The sleeve 31 is provided with an external layer of material 3| which when heated by the filament emits electrons. The cathode assembly is closely surrounded by the grid and a plate or anode 32 mounted on support member [5 is disposed about the grid. A getter tab 33 may be supported on an arm 34 secured to the support I5.

In accordance with the present invention the anode 32 may be of cylindrical form as shown in Fig. 2 and having extensions 35 and 35 welded together and to the support member l5.

As shown in Fig. 3 the double mesh wall provides relatively long paths 3? which paths are indirect or tortuous thus providing surfaces to receive electrons and permit the passage of heat rays and thereby dissipating the heat and .pre-

venting its reflection to the grid and also preventing the escape of electrons.

Fig. 4 shows what is termed a twill mesh which consists of a combined double wall giving long tortuous passages 38 with the same desirable result as is obtained by the double wall mesh. A modified form of anode material is shown in Fig. 5 which illustrates a sheet of material having elongated slots or tortuous passages 39 which may be punched or otherwise formed in a sheet of metal. If desirable several sheets or walls having passages may be used so that the apertures are disposed in staggered relation.

Good results have been obtained by using a double sheet of mesh material and that the mesh termed the twill weave provides the required tortuous apertures and gives almost as satisfactory results as a double wall of the ordinary mesh. It has been found, however, that a plate made of a double wall of mesh has considerable advantage as to strength and holds its cylindrical shape and retains its relative position with respect to the other electrodes in a more effective manner.

Although a preferred embodiment of the invention is shown and described herein it is to be understood that modifications may be made 7 therein without departing from the spirit and scope of the invention as set forth in the appended claims. 

